1. Field of the Invention
The present invention relates to a display apparatus and a display drive method thereof. In particular, the invention relates to a display apparatus and a drive control method thereof, the apparatus being provided with a display panel having a plurality of current control type optical elements arranged thereon to display image information.
2. Description of the Related Art
In recent years, light weight and thin type display devices which consume a lower amount of electric power are conspicuously prevalent as monitors and displays of personal computers and video equipment. In particular, liquid crystal display (LCD) apparatuses are widely applied as display devices for mobile phones, digital cameras, personal data assistants (PDA's), and portable devices (mobile handsets) such as electronic dictionaries.
As a next-generation display device which follows such an LCD apparatus, research and development have been briskly made toward a full-scale popularization of a self-luminous type display device (a self-luminous type display) provided with a display panel in which organic electroluminescent elements (organic EL elements), inorganic electroluminescent element (inorganic EL elements) or self-luminous type optical elements such as light emitting diodes (LED) are arranged in a matrix form.
In particular, a self-luminous type display apparatus to which an active matrix drive mode is applied has a higher display response speed than that of the above-described liquid crystal display. Further, the self-luminous type display apparatus does not have view field angle dependency, and can achieve an increase in luminance/contrast and in fineness of a display image quality. Furthermore, the self-luminous type display apparatus does not require the backlight used in a liquid crystal display, and hence the self-luminous type display has very advantageous characteristics in the application to portable devices that a further reduction in a thickness and a weight and/or a further decrease in power consumption is possible.
FIG. 25 is schematic structural diagram showing a primary part of an active matrix type self-luminous type display apparatus in a prior art.
FIG. 26 is a timing chart showing one example of a display drive method of the active matrix type self-luminous type display apparatus in the prior art.
FIG. 27 is a timing chart showing another example of the active matrix type self-luminous type display apparatus in the prior art.
Here, in FIGS. 26 and 27, for ease of comparison with embodiments which will be described later, there is shown a display drive method in the case where the apparatus has a configuration in which a display panel has twelve rows (first to twelfth rows) of display pixels arranged. In FIGS. 26 and 27, symbol K denotes a positive integer. Incidentally, hatching is provided for clarifying a writing operation and display operation of image data in each row, and writing operation and display operation of blanking data.
An active matrix type display apparatus such as a liquid crystal display apparatus and a self-luminous type display apparatus generally has, as shown in FIG. 25, a configuration comprising: a display panel 110P in which a plurality of display pixels EMp are arranged in two dimensions in the vicinity of intersections of a plurality of scanning lines SLp and data lines DLp arranged in row and column directions; a scanning driver 120P which is connected with the scanning lines SLp; and a data driver 140P which is connected with the data lines DL.
For example, as shown in FIG. 26, in a display drive control in the display apparatus having such a configuration, display pixels EMp for each row are sequentially set to a selection state by sequentially applying a selection level scanning signal Ssel to the scanning lines SLp in each row from the scanning driver 120P in the beginning. Then, in synchronization with the selection timing of each row, a gradation voltage Vpix corresponding to image data (display data) in the row is applied to the data line DLp in each column from the data driver 140P, whereby a voltage component based on the gradation voltage Vpix is held to each of the display pixels EMp (a image data writing period). As a consequence, a gradation control corresponding to the above-described voltage component is performed in each display pixel EMp, so that a display operation (light emitting operation) corresponding to the image data is performed and desired image information is displayed on the display panel.
Subsequently, the display pixels EMp for each row are set to a non-selection state by sequentially applying a non-selection level scanning signal Ssel to the scanning lines SLp from the scanning driver 120P. However, when the voltage component written immediately previously is held in each of the display pixels, the display operation corresponding to the image data continues (a image display period), and the operation continues until next image data is written in the display pixels EMp in each row. This type of display control method is referred to as a hold type.
In such a hold type display control method, there is provided a characteristic such that flickering is hardly generated in the display operation of static images because the display operation (the light emitting operation) corresponding to the image data continues in almost all the period of one frame period. However, on the other hand, in the display of moving images, image information displayed in the previous frame period can become visually recognized more easily as an afterimage, and consequently, blurs and stains of the image information occur, which will lead to the deterioration of display image quality.
Then, as a display drive method for improving the display image quality by suppressing blurs and stains in the display operation of moving images, there is known a technique for performing, in one frame period, an operation (a blanking data writing period) of supplying from a data driver to each data line blanking data for performing an operation (a light emitting operation) of displaying each display pixel EMp at the lowest gradation, or for performing a non-display operation (a non-light emitting operation) and a black display operation (a black display period) based on the blanking data, in addition to the above-described image data writing period and image display period. As a consequence, a definite length of a black display period is inserted into the one frame period and a blank display state is set. Accordingly, a display drive method (referred to as a “pseudo-impulse type display drive method” for convenience) in which the image display period is relatively reduced can be realized and a display image quality in the display operation of moving images can be improved.
However, in such a pseudo-impulse type display drive method, as shown in FIG. 27, it is required to set, in one frame period, the writing period of the blanking data supplied from the data driver and the black display period as well as the writing period of the image data supplied from the data driver and the image display period. For this reason, only the writing operation of the image data supplied from the data driver and the image display operation are performed in one frame period as shown in FIG. 26. As compared with the case in which the black display operation is not performed, the time which can be allocated to the writing operation of the image data is shortened, and as a consequence, it becomes necessary to write the image data at a high speed by heightening a drive frequency (that is, the drive frequency of the display apparatus) associated with the writing operation of the image data.
In this manner, when the writing period of the image data (display data) is shortened so that the writing operation must be performed at a high rate, a writing insufficiency occurs owing to the insufficiency of the time for writing the image data to each display pixel with respect to a signal delay generated resulting from a CR time constant produced by a resistance component parasitic on signal wirings of a display panel and a capacity component, etc. Consequently, gradation display corresponding to the image data may not be executed properly.